Load distribution device, load distribution system, load distribution method, and load distribution program

Abstract

In the present invention, an SMF (33) receives from a UE (41) a request to establish a PDU session including a PDU session ID, selects a UPF (21) to serve as a load distribution destination, from among a plurality of UPFs (21), responds to the UE (41) with address information of a gateway (36) for relaying the PDU session, and notifies the gateway (36) of information about the correspondence between the PDU session ID and the selected UPF (21), thus performing control so that a data signal which arrives at the gateway (36) from the UE (41) via the PDU session is forwarded to the selected UPF (21).

Description

Technical Field

[0001] The present invention relates to a load distribution device, a load distribution system, a load distribution method, and a load distribution program.

Background Art

[0002] Load distribution technology is a technology for improving integrated processing capabilities by a load distribution device such as a load balancer distributing a load to any one of a plurality of processing servers serving as load distribution destinations. After processing the assigned load, the processing server will process another load. Therefore, in order to sequentially process many loads, it is common for the processing server to adopt a stateless method in which it does not need to maintain the state of the result after returning the processed result. Hereinafter, a stateless load distribution technology will be exemplified.

[0003] Non-Patent Document 1 describes a method of realizing load distribution in units of services using a container orchestrator such as Kubernetes in Web-based protocols such as HTTP (Hypertext Transfer Protocol) and HTTPS (Hytertext Transfer Protocol Secure). Non-Patent Document 2 describes a mechanism for executing load distribution by an appliance of a load balancer manufacturer for relatively popular protocols among the protocols used in public communication networks such as SIP (Session Initiation Protocol).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a network system corresponding to the fifth-generation communication standard (5G: 5th Generation) of wireless communication such as mobile phones, 5GC (5th Generation Core network) has been proposed. It is considered to construct a load distribution destination processing server as a container-type application called UPF (User Plane Function) within 5GC. At this time, it is required to satisfy the following requirements. (Requirement 1) From the perspective of concealing the internal network configuration for security measures in 5GC, it is necessary to conceal the configuration of UPF. (Requirement 2) In 5G, the C-plane (control signal) and the U-plane (user data) are separated. Therefore, in the call control process of the PDU (Protocol Data Unit) session, which is a communication connection in 5G, load distribution that coordinates a stateful C-plane and U-plane is required. Hereinafter, (Requirement 1) will be described with reference to FIGS. 13 and 14.

[0006] FIG. 13 is a configuration diagram showing an example of a 5GC system. The 5G C system is configured by connecting, via a network, a Data Network (DN) 11, User Plane Functions (UPFs) 21 - 23, a next Generation NodeB (gNB) 31, an Access and Mobility Management Function (AMF) 32, a Session Management Function (SMF) 33, and a User Equipment (UE) 41 as network functions (NFs). The DN 11 is a variety of networks outside 5G, such as the Internet or a system equivalent to a telephone exchange like the IP Multimedia Subsystems (IMS). The UPFs 21 - 23 are user plane functions that transfer data (U plane) transferred from users and operate as processing servers for load distribution destinations. The AMF 32 is an access and mobility management function that manages terminal location information and authentication information. The SMF 33 is a load distribution device with a session management function that manages PDU sessions in 5G.

[0007] The gNB 31 is a 5G base station that provides New Radio (NR) and accommodates the UE 41. The UE 41 is a user terminal operated by a user and is used to transmit and receive communication data to and from the UPF 21. Here, if there is no terminating device between the gNB 31 and the UPFs 21 - 23, the IP address information of the UPFs 21 - 23 will be disclosed to the outside (the UE 41 side) and will not meet requirement 1.

[0008] Figure 14 is a configuration diagram in which a Network Address Translation (NAT) device 34 is added to the 5G C system of Figure 13. The NAT device 34 publishes one global IP address on the UE41 side and performs address conversion by NAT between the gNB31 and the UPF21-23. As a result, the IP address information of the UPF21-23 satisfies (Requirement 1) because the NAT device 34 conceals the information. However, since the NAT device 34 does not perform load distribution, (Requirement 2) is not satisfied.

[0009] (Requirement 2) will be described with reference to FIGS. 15 and 16. First, there are a variety of communication protocols used in public communication services. For the following representative protocols, load distribution can be performed by existing load balancer products. · Conventional general Web-based protocols such as HTTP and HTTPS · VoIP (Voiceover IP) protocols such as SIP

[0010] On the other hand, there is no existing load balancer product that can support the diverse protocols existing for each NF like 5G. That is, there is no load distribution that coordinates the stateful C-plane and U-plane of 5G. If a load balancer product that can support diverse protocols is realized with containers, each container needs to have a unique IP and communicate with the opposing device, which is costly.

[0011] FIG. 15 is a configuration diagram in which a 4G (4th Generation Mobile Communication System) system is connected to the 5GC system of FIG. 13. In a non-standalone 5GC, a 4G system also coexists. As the 4G system, an eNB (evolved Node B) 35 accommodating the UE42 is connected to the UPF21-23 in the same manner as the gNB31. Note that the UPF21-23 functions as an S-GW (Serving Gateway) and a P-GW (Packet data network Gateway) for 4G.

[0012] FIG. 16 is a configuration diagram in which signals in the C plane and signals in the U plane are added to the system of FIG. 15. The C plane indicated by the dashed arrow notifies the UE41 of the selection result (load distribution destination) of the UPF21 responsible for the U plane as the session partner for the PDU session establishment request from the UE41 via the illustrated path. The U plane indicated by the solid arrow is the communication between the UE41 and the DN11 through the PDU session via the UPF21 notified in the U plane.

[0013] In 5G, the C plane and the U plane are separated, and the call control process of the PDU session is established by the cooperation of the stateful C plane and U plane. Therefore, even if it is attempted to load-balance the U plane via the UPF21 selected in the C plane, it cannot be realized only with the session information of the U plane. For example, assume that the communication volume between the UE41 and the DN11 increases. If the session information of the U plane is associated with the fixed UPF21, it is difficult to load-balance some of the traffic processed by the UPF21 to other UPF22, 23. That is, a load distribution mechanism considering both the C plane and the U plane is required.

[0014] Therefore, the main object of the present invention is to achieve stateful load distribution while hiding the internal network information of the load distribution destination.

Means for Solving the Problems

[0015] In order to solve the above problems, the load distribution device of the present invention has the following features. The present invention is a load distribution device that manages information including the ID of a session, receives a session establishment request including the ID of the session from a user terminal, selects a processing server as a load distribution destination from a plurality of processing servers, responds to the user terminal with the address information of the gateway that relays the session, By notifying the gateway of the correspondence information between the ID of the session and the selected processing server, It is characterized in that control is performed so that a data signal arriving at the gateway from the user terminal via a session is transferred to the selected processing server.

Effects of the Invention

[0016] According to the present invention, it is possible to achieve stateful load distribution while concealing the internal network information of the load distribution destination.

Brief Description of the Drawings

[0017]

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Mode for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0019] FIG. 1 is a configuration diagram showing the 5GC system of this embodiment. The 5GC system of FIG. 1 replaces SMF33 with SMF33X in the 5GC system of FIG. 13 and adds a gateway 36 between gNB31 and UPF21-23. As a result, the gateway 36 conceals the configuration of UPF21-23, which is a group of containers targeted for load distribution, from the external UE41. Furthermore, SMF33X is provided with a function of communicating (notifying) the state information of the C plane to the gateway 36. The state information of the C plane is the adjustment result of the PDU session, for example, the correspondence information between the UPF21 selected as the load distribution destination and the PDU session ID (TE-ID) described later. Thereby, the gateway 36 can execute the load distribution of the U plane in consideration of both the C plane and the U plane.

[0020] SMF33X manages the information including the ID of the PDU session. That is, SMF33X controls so that the data signal that has reached the gateway 36 via the PDU session from the UE41 is transferred to the selected UPF (hereinafter, it will be described that UPF21 is selected). · SMF33X receives an establishment request for a PDU session including the ID of the PDU session from the UE41, and selects UPF21 as the load distribution destination from a plurality of UPF21, 22, 23. · SMF33X responds to the UE41 with the address information of the gateway 36 that relays the PDU session. · SMF33X notifies the gateway 36 of the correspondence information between the ID of the PDU session and the selected UPF21. The gateway 36 converts the transmission destination of the data signal received from the UE41 via the PDU session from its own address information to the address information of the UPF21 selected by referring to the correspondence information based on the ID of the PDU session.

[0021] FIG. 2 is a configuration diagram in which a proxy 37 is added to the 5GC system of FIG. 1. The proxy 37 is connected between the SMF33X and the UPF21-23. The function of notifying the state information of the C plane to the gateway 36, which was provided in the SMF33X in FIG. 1, is provided in the proxy 37 in FIG. 2. The proxy 37 receives the PDU session establishment request from the UE 41, transfers the establishment request to the SMF 33X, and notifies the gateway 36 of the correspondence information between the PDU session ID and the UPF 21 selected by the SMF 33X on behalf of the SMF 33X. This can reduce the impact on the existing SMF 33 and reduce the amount of implementation changes to the existing SMF 33.

[0022] Hereinafter, taking the PDU session establishment procedure (standard sequence) of the standard specification as an example, the specific processing of the 5GC system in FIGS. 1 and 2 is shown. Note that the PDU session establishment procedure is defined in Section 4.3.2.2, "UE Requested PDU Session Establishment" of the standard specification "ETSI TS 123 502" published by the European Telecommunications Standards Institute (ETSI). Hereinafter, FIGS. 3 to 5 are sequence diagrams showing the standard sequence. By executing in the order of FIG. 3 → FIG. 4 → FIG. 5, the PDU session is established in the C plane, and the U plane flows through the PDU session.

[0023] FIG. 3 is the first sequence diagram in which the 5GC system executes the PDU session establishment procedure. Note that in FIG. 3, the following configurations are further added to the 5GC system in FIG. 13. · The RAN (Radio Access Network) 51 is an access network device arranged in a base station or the like. · The PCF (Policy Control Function) 52 is a policy control device. · The UDM (Unified Data Management) 53 is a device that holds subscriber-related information.

[0024] S101 is a process of requesting the establishment of a PDU session including a PDU session ID (TE-ID) from the UE 41 to the AMF 32 (PDU Session Establishment Request). S102 is a process of the AMF 32 selecting the SMF 33X (SMF selection). S103 is a process of the AMF 32 requesting session management for the request of S101 from the SMF 33X (Nsmf_PDUSession_CreateSMContext Request). S104 is a process of the SMF 33X reading and responding with subscriber information corresponding to the session management requested in S103 from the UDM 53 (Subscription retrieval / Subsucription for updates). S105 is a process of the SMF 33X responding to the request of S103 including the subscriber information of S104 to the AMF 32 (Nsmf_PDUSession_CreateSMContext Response). S106 is a process of each device in the 5GC system performing authentication and authorization of the PDU session establishment (PDU Session authentication / authorization).

[0025] S107a is a process of the SMF 33X selecting the PCF 52 to be processed in S110a of FIG. 4 (PCF selection). S107b is a process of the SMF 33X setting an SM policy association to the PCF 52 (SM Policy Association Establishment), or a process of modifying the SM policy association initiated by the SMF 33X (SMF initiated SM Policy Association Modification). S108 is a process of the SMF 33X selecting the UPF 21 to be processed in S110a of FIG. 4 (UPF selection). S109 is a process of changing the SM Policy Association initiated by SMF33X from SMF33X to PCF52 (SMF initiated SM Policy Association Modification). After the process of S109, it continues with the process in Figure 4.

[0026] Figure 4 is the second sequence diagram in which the 5GC system executes the PDU session establishment procedure. S110a is a process of requesting the setup and modification of the N4 session from SMF33X to UPF21 (N4 Session Establishment / Modification Request). S110b is a process of sending the response to S110a from UPF21 to SMF33X (N4 Session Establishment / Modification Response). S111 is a process of sending an ACK to the PDU setup request from SMF33X to AMF32 (Namf_Communication_N1N2MessageTransfer). This ACK contains the IP address of UPF21 assigned to the PDU session ID. S112 is a process of sending a N2 PDU session request (NAS message) from AMF32 to RAN51 (N2 PDU Session Request (NAS msg)).

[0027] S113 is a process of setting up the resources of RAN51 from RAN51 to UE41 (AN-specific resource setup (PDU Session Establishment Accept)). S114 is a process of sending the response to S112 from RAN51 to AMF32 (N2 PDU Session Request Ack). S114b is a process of sending the first uplink data from UE41 to UPF21. S115 is a process that requests an update of the PDU session from AMF32 to SMF33X (Nsmf_PDUSession_UpdateSMContext Request). S116a is a process that requests a change of the N4 session from SMF33X to UPF21 (N4 Session Modification Request). S116b is a process that sends a response to S116a from UPF21 to SMF33X (N4 Session Modification Response).

[0028] Figure 5 is the third sequence diagram in which the 5GC system executes the PDU session establishment procedure. S116c is a process that registers the PDU session from SMF33X to UDM53 (Registration). S116d is a process that sends the first downlink data from UPF21 to UE41. S117 is a process that responds to S115 from SMF33X to AMF32 (Nsmf_PDUSession_UpdateSMContext Response). S118 is a process that notifies the PDU session state from SMF33X to AMF32 (Nsmf_PDUSession_SMContextStatusNotify). S119 is a process that configures the IPv6 address from SMF33X to UPF21 and UE41 (IPv6 Address Configuration). S120 is a process that modifies the SM policy association initiated by SMF33X from SMF33X to PCF52 (SMF initiated SM Policy Association Modification). S121 is a process that cancels the registration of S116c from SMF33X to UDM53 (Unsubscription).

[0029] The main differences between the PDU session establishment procedure of this embodiment and the standardized specification are as follows three points. (Difference 1) Add a procedure for the SMF33X to notify the gateway 36 of the correspondence information between the selected UPF21 as the load distribution destination and the PDU session ID (TE-ID). (Difference 2) Add a procedure for the SMF33X to notify the UE41 of the IP address of the gateway 36. (Difference 3) The gateway 36 transfers the U-plane data to the UPF21 corresponding to the PDU session ID. After the processing of (Difference 1), the load distribution system of this embodiment executes the processing of (Difference 2) to complete the preparation for data transfer. After the preparation, the load distribution system of this embodiment executes the processing of (Difference 3). Thereby, a load distribution realization method for a PDU session that coordinates the C-plane and the U-plane while concealing the UPF21 configuration is realized.

[0030] FIG. 6 is a configuration diagram highlighting the path of the C-plane flowing from the UE41 to the UPF21 for the 5GC system of FIG. 1. The C-plane flows in the following order. · UE41 → gNB31 → AMF32: The signal of S101 flows (requesting the setting of the PDU session). · AMF32 → SMF33X: The signal of S103 flows (requesting session management for the request of S101). Here, the SMF33X selects the UPF21 (the load distribution destination) responsible for the U-plane (S108). Note that the SMF33X may refer to the current load status of the UPF21-23 and change the previously determined load distribution destination UPF21 to the UPF22 or UPF23. · SMF33X → UPF21: The signal of S110a flows (requesting the setting and change of the N4 session).

[0031] FIG. 7 is a configuration diagram highlighting the path of the C-plane flowing from the UE41 to the UPF21 for the 5GC system of FIG. 2. The signal of S110a in FIG. 6 (SMF33X→UPF21) flows through the path of SMF33X→Proxy 37→UPF21 in FIG. 7. The flow of other signals is the same in FIGS. 6 and 7.

[0032] FIG. 8 is a configuration diagram emphasizing the return path of the C plane in FIG. 6. The C plane flows in the following order. · UPF21→SMF33X: The signal of S110b flows (sends a response to S110a). · SMF33X→AMF32: The signal of S111 flows (sends an ACK to the PDU setting request). The signal of S111 in the standard sequence included the IP address of UPF21 responsible for the U plane for the PDU session ID. The load balancing system of this embodiment includes the IP address information of Gateway 36 in the signal of S111 instead of the IP address of UPF21 (Difference 2). The IP address information of Gateway 36 is, for example, the IP address of the interface adjacent to gNB31 of Gateway 36 that aggregates UPF21. As a result, the IP address information of Gateway 36 is also included in the subsequent S112 and S113 signals and is notified to UE41. Also, since the IP address of UPF21 is not notified to UE41, the configuration of UPF21 is hidden.

[0033] · Add a procedure for notifying the correspondence information between UPF21 selected as responsible for the U plane and the PDU session ID (TE-ID) to the standard sequence between SMF33X and Gateway 36 (Difference 1). This procedure of (Difference 1) is preferably executed between S110b and S111 and is completed before S113 at the latest. · AMF32→gNB31 (RAN51): The signal of S112 flows (sends an N2 PDU session request). · gNB31 (RAN51)→UE41: The signal of S113 flows (configures the resources of RAN51).

[0034] FIG. 9 is a configuration diagram highlighting the return path of the C plane in FIG. 7. The following are the differences between FIGS. 8 and 9, and the flow of other signals is the same in FIGS. 8 and 9. · The signal of S110b in FIG. 8 (UPF21→SMF33X) flows through the path of UPF21→Proxy 37→SMF33X in FIG. 9. · The device that executes the procedure (difference point 1) of notifying the gateway 36 of the correspondence information between the selected UPF21 as the load distribution destination and the PDU session ID (TE-ID) is replaced by the proxy 37 from the SMF33X.

[0035] FIG. 10 is a configuration diagram highlighting the path of the U plane transmitted after the C plane in FIG. 8. First, S114b (First Uplink Data) of the standard sequence was directly notified from the UE41 to the UPF21. On the other hand, in FIG. 10, the uplink data such as the first uplink data of S114b is transmitted in the order of UE41→gNB31→gateway 36→UPF21→DN11. Here, when the gateway 36 receives the U plane data from the UE41 via the PDU session, it determines the UPF21 of the transfer destination (load distribution destination) of the U plane data by address conversion processing (NAT: Network Address Translation), and transfers the U plane data to the UPF21 (difference point 3). The address conversion processing is a process in which the gateway 36 that refers to the correspondence information notified in (difference point 1) converts the PDU session ID (TE-ID) into the IP address of the corresponding UPF21. Thereby, the configuration of the UPF21 is hidden from the UE41.

[0036] Also, similarly, S116d (First Downlink Data) of the standard sequence passes through the gateway 36 in the order of DN11→UPF21→gateway 36→gNB31→UE41 instead of being directly notified from the UPF21 to the UE41. Therefore, for the gateway 36, the PDU session information for the downlink data is notified from the SMF 33X after S116b. Thereby, the PDU session for the downlink data is established.

[0037] FIG. 11 is a configuration diagram highlighting the path of the U plane transmitted after the C plane of FIG. 8. Regardless of the presence or absence of the proxy 37, each data in FIG. 11 is transmitted through the same path as in FIG. 10.

[0038] FIG. 12 is a hardware configuration diagram of each device (such as the SMF 33X and the gateway 36) of the 5GC system according to the present embodiment. Each device of the 5GC system is configured as a computer 900 having a CPU 901, a RAM 902, a ROM 903, an HDD 904, a communication I / F 905, an input / output I / F 906, and a media I / F 907. The communication I / F 905 is connected to an external communication device 915. The input / output I / F 906 is connected to an input / output device 916. The media I / F 907 reads and writes data from a recording medium 917. Further, the CPU 901 controls each part by executing a program (also called an application or an app for short) read into the RAM 902. And this program can be distributed via a communication line or recorded on a recording medium 917 such as a CD-ROM and distributed.

[0039] [Effect] The present invention is an SMF 33X that manages information including the ID of a PDU session, receives a PDU session establishment request including the ID of the PDU session from the UE 41, selects a UPF 21 as a load distribution destination from a plurality of UPFs 21, responds to the UE 41 with the address information of the gateway 36 that relays the PDU session, by notifying the gateway 36 of the correspondence information between the ID of the PDU session and the selected UPF 21, It is characterized in that the data signal reaching the gateway 36 from the UE 41 via the PDU session is controlled to be transferred to the selected UPF 21.

[0040] As a result, the external UE 41 is notified of the address information of the relaying gateway 36 without being notified of the address information of the selected UPF 21. Therefore, in an architecture where the C plane and the U plane are separated, stateless load distribution can be realized while concealing the internal network information of the load distribution destination.

[0041] The present invention is a load distribution system having an SMF 33X and a gateway 36, wherein the gateway 36 converts the transmission destination of the data signal received from the UE 41 via the PDU session from its own address information to the address information of the selected UPF 21 by referring to the correspondence information based on the ID of the PDU session.

[0042] As a result, the impact of network configuration changes during the scale-out of the UPF 21 or the like can be avoided without affecting the UE 41, which is the opposing device.

[0043] The present invention is characterized in that the load distribution system further has a proxy 37, wherein the proxy 37 receives a PDU session establishment request from the UE 41, transfers the establishment request to the SMF 33X, and notifies the gateway 36 of the correspondence information between the ID of the PDU session and the selected UPF 21 by the SMF 33X instead of the SMF 33X.

[0044] As a result, the processing performed by the existing SMF 33X is reduced, and the development cost of modifying the existing SMF 33X can be reduced.

Explanation of Signs

[0045] 11 DN 21-23 UPF (Processing Server) 31 gNB 32 AMF 33,33X SMF (Load Balancing Device) 34 NAT Device 35 eNB 36 Gateway 37 Proxy 41,42 UE (User Equipment) 51 RAN 52 PCF 53 UDM

Claims

1. A load balancer for managing information including the ID of a session, comprising: receiving a session establishment request including the ID of the session from a user terminal, selecting a processing server as a load balancing destination from a plurality of processing servers, responding to the user terminal with the address information of a gateway that relays the session, notifying the gateway of the correspondence information between the ID of the session and the selected processing server, characterized in that control is performed such that a data signal arriving at the gateway from the user terminal via the session is transferred to the selected processing server. Load balancer.

2. A load balancing system having the load balancer according to Claim 1 and the gateway, wherein: the gateway selects the transmission destination of a data signal received from the user terminal via a session from its own address information and converts it into the address information of the processing server selected by referring to the correspondence information based on the ID of the session. Load balancing system.

3. The load balancing system further includes a proxy, wherein the proxy receives the session establishment request from the user terminal, transfers the establishment request to the load balancer, and notifies the gateway of the correspondence information between the ID of the session and the processing server selected by the load balancer instead of the load balancer. The load balancing system according to Claim 2.

4. A load balancing method executed by a load balancer for managing information including the ID of a session, wherein: the load balancer receives a session establishment request including the ID of the session from a user terminal, selects a processing server as a load balancing destination from a plurality of processing servers, responds to the user terminal with the address information of a gateway that relays the session, notifies the gateway of the correspondence information between the ID of the session and the selected processing server, characterized in that control is performed such that a data signal arriving at the gateway from the user terminal via the session is transferred to the selected processing server. Load balancing method.

5. A load balancing program for causing a computer to function as the load balancer according to Claim 1.

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